40 hp johnson spark plugs

[amy]

I have a 75' johnson 40hp

I have a 75' johnson 40hp the top cylinder is burning the plug very black and powdery. the bottom one is clean with a little wetness to it. Also has a very bad miss as you try to feed it throttle> Idles great.chk compression 100pds both cylinders.Cleaned carb. now what can I do?It also is getting spark.

 

[piperjak]

"I'm a believer in float l

"I'm a believer in float levels. If it is slightly high, it could cause your problem. I like to check the source that is supplying the fuel. For some reason - it is getting a bit too much fuel. Hard to tell from what you describe. Could also be a weak spark on that cylinder. A bad coil could cause this also. Just some basic ideas!!"

 

[amy]

they were brand new spark plug

they were brand new spark plugs. I did just adjust the float but this float had sat for numerous years with out running. Two weeks ago it ran great but the float was getting stuck on the far side of the bowl. could this float be logged from sitting in fuel for so long?

 

[piperjak]

Yes it could. That could cause

Yes it could. That could cause a high float level too. How did you adjust the float level? Does the float have a shellac looking coating on it?

 

[amy]

"Yes the float looks like it w

"Yes the float looks like it was varnished. I adjusted the float by bending the brass piece that holds it,trying to keep it away from the far side of the bowl.I made sure that when the float was all the way up that the needle was closed at least I thought so.I know that is probably not how you do it.I bought a carb rebuild kit but it was the wrong one,geuss I better get the right one and install it!!!"

 

[joereeves]

A black fluffy soot like cover

A black fluffy soot like covering of the plug indicates weak ignition.

 

[amy]

should I start with the coil?

should I start with the coil? Or go beyond? Can I test with Ohm meter?

 

[piperjak]

How much do you want to spend?

How much do you want to spend? Coils are $30 bucks each. I would just get a new one.
You will need a new carb kit. There are pleanty of references on this site as to how to eyeball adjust it. I would replace the points and condenser too ..that way you have a good ignition source for years to come and not have to worry about using the oars.